Being a Serious JFKA Researcher, I went back through my Kindle edition of Carpenter's book. He does not mention the Habana Bar or Pena, presumably because the book was published in 2014 and Pena's HSCA testimony did not become public until the 2017 document release.
He does mention Ferrie 523 times and I, as a Serious JFKA Researcher, scrolled through all 523 references. Carpenter does not shy away from the various folks who said they had seen Ferrie and Shaw together, or from the several who knew one or both of them very well and said they had never heard one mention the other. Carpenter doesn't state a firm conclusion, but there just doesn't seem to be any solid evidence. Many people apparently believe the confusion is that Ferrie was seen in the company of Bannister - who, like Shaw, was tall and gray-haired.
The book gives you a sense of how very important, respected and even beloved Shaw was. Yes, he was heavily into the gay scene and the book recounts one of his kind-of-clumsy efforts to pick up a young guy, but he certainly didn't "need" Ferrie and would have descended far below his social, economic and intellectual class to have openly associated with him. The Shaw who emerges from the book simply would not have descended to the level of frequenting the Habana Bar with Ferrie.
FWIW, when Ferrie was first asked about Clay Shaw, his response was "Who's Clay Shaw?"
I think I'm going to bump my Amazon review to 4 stars. Carpenter worked 18 years on this book, and it is really quite astonishing.